They were women. Not minor female children.
At least accordingly to this link, the trend for dial-painters was to be teenagers. Some started as early as their fourteens. It makes sense considering the 1920s, when adult women were expected to stay at home and take care of children, not to be part of the workforce. So odds are that "radium girls" is accurate, because most of them were not adult women.
Wikipedia, and the sources that Wikipedia is relying on, are also rather consistently calling them "Radium girls". This is clearly a fixed expression, that shouldn't be decomposed like you're doing.
And even if we disregard both things above (we should not), your "small correction" boils down to "I'll vomit an «ackshyually» to boss the other user around on language usage, disregarding what they say to whine about how they say it". This is simply not contributive.
They could get a .ck domain instead and move to queer.as.fu.ck, no?